Fluid Dispensing Apparatus

ABSTRACT

A fluid dispensing apparatus is configured to dispense a predetermined volume of fluid, and includes a fluid reservoir to hold a fluid to be dispensed, a dispense tube to dispense the fluid, and an elevator mechanism. The fluid reservoir receives a fluid from a fluid supply. A dispense tube has a dispense outlet, and is connected to an outlet port on the fluid reservoir. The elevator mechanism changes a relative vertical displacement between the dispense outlet and the outlet port. Particularly, a processor controls the elevator mechanism to raise the dispense tube to a raised filling position to prevent fluid flow from the dispense outlet, and lower the dispense tube to a lowered dispensing position to dispense the fluid.

RELATED APPLICATIONS

This application is a continuation-in-part application and claimspriority from U.S. application Ser. No. 11/199,636 entitled, “FluidDispensing Apparatus.” The '636 application, which was filed on Aug. 9,2005, is expressly incorporated herein by reference in its entirety.

BACKGROUND

The present invention relates generally to fluid dispensing devices, andparticularly to volumetric fluid dispensing devices that dispense apredetermined volume of fluid.

There are many types of fluid dispensing devices currently available.For example, one type of fluid dispensing device that is currently inwidespread use is known as a positive displacement filler. Some positivedisplacement fillers employ a piston and cylinder arrangement toalternately draw and expel a fluid to be dispensed. The piston draws thefluid into the cylinder when it moves in one direction (e.g., a downwardstroke), and expels the fluid from the cylinder when it moves in anopposite direction (e.g., an upward stroke). The expelled fluid entersthe bottle or container through a tube connected to the cylinder. Othertypes of positive displacement fillers may employ rotary pumps ordiaphragm pumps to alternately draw and expel the fluid.

Another type of fluid dispensing device is known as a time/pressurefiller. Generally, these types of devices include a fluid holding tankthat maintains the fluid at a relatively constant pressure. Fluid isdispersed into the bottle or container through a length of compressibletubing connected to the tank. A pinch-type valve operates on the tubingto alternately allow and restrict the flow of fluid into the bottle.Operation of the valve may be controlled using a timer, such that thevalve opens and closes for predetermined lengths of time. Because thepressure is maintained at a relatively constant level within thereservoir, the same amount of fluid should be dispensed whenever thevalve opens.

A third type of fluid dispensing device is known as a volumetric fluiddispensing device. These types of devices first measure a predeterminedvolume of fluid before dispensing the fluid into the bottle orcontainer. Generally, a fill tube is disposed between the reservoir andthe bottle that holds the predetermined volume of fluid to be dispensed.The fill tube may comprise a compressible tube with a pinch-type valve.When the fill tube fills to a specified level, which may be determinedby one or more sensors, for example, the pinch-type valve opens topermit the measured fluid to flow through the fill tube and into thebottle or container. Once the fluid is dispensed, the valve closes tostop the flow of fluid until the fill tube once again holds thepredetermined amount of fluid.

Another type of volumetric fluid dispensing device uses the net weightof a container or bottle that receives the dispensed fluid.Particularly, the empty bottle or container rests on a balance. As thefluid enters the bottle or container, the balance detects the change inthe bottle's weight. When the balance detects that the bottle and fluidhave achieved a specified weight, a pinch-type valve closes to stop theflow of fluid into the bottle.

Each of these types of fluid dispensing devices have their advantages,such as speed and/or accuracy, but they also have various disadvantages.Positive displacement fillers, for example, necessarily require that thefluid being dispensed contact the mechanical moving parts of the device.Volumetric fluid dispensing devices use pinch-type valves that tend towarp or degrade the compressible tubing over time. Thus, the fluid beingdispensed with these types of devices may become contaminated withundesirable particulate matter. The fluid paths of volumetric fluiddispensing devices cannot be steam sterilized because acceptablematerials used in constructing some portions of the dispensing device,such as the fluid reservoir, may melt at autoclave temperatures.Therefore, the user cannot rinse the fluid path with water forinjection, and must introduce critical components of the dispensingdevice to a sterile filling area via an air lock. Additionally, the“hammering” effect of the pinch-type valve could possibly damage somefluids flowing through the compressible tube, for example, protein-basedsolutions with long molecular chains. Net weight devices are highlyaccurate, but they require tedious, time-consuming calibrationprocedures. Further, the fill rate of a net weight device is generallynot high enough to warrant their commercial use. Thus, these types ofdevices are usually relegated to being used as a statistical tool.

SUMMARY

The present invention comprises a fluid dispensing apparatus thatincludes a fluid reservoir connected to a fluid supply, a dispense tubeconnected to an outlet port on the fluid reservoir, and an elevatormechanism to change a relative vertical displacement between thedispense outlet and the outlet port on the fluid reservoir. In oneembodiment, the fluid reservoir receives fluid from the fluid supplythat will be dispensed into a container. The dispense tube has ameasurement portion to measure a predetermined volume of fluid to bedispensed, and a dispense portion. The dispense portion includes adispense outlet to dispense the predetermined volume of fluid. Theelevator mechanism changes the relative vertical displacement betweenthe dispense outlet and the outlet port on the fluid reservoir byraising and lowering the dispense tube.

To control the elevator mechanism, the processor may generate controlsignals to raise or lower the elevator mechanism. Particularly, theprocessor controls the elevator mechanism to raise the dispense tube toa raised filling position to prevent fluid flow from the dispenseoutlet. While the dispense tube is in the raised filling position, theprocessor generates controls signals to fill the measurement portion ofthe dispense tube with the predetermined volume of fluid from the fluidreservoir. Once the measurement portion of the dispense tube has thepredetermined volume of fluid, the processor generates signals tocontrol the elevator mechanism to lower the dispense tube to a lowereddispensing position. In this lowered dispensing position, thepredetermined volume of fluid is dispensed from the dispense tube andinto a receptacle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1B illustrate a fluid dispensing apparatus according to a firstembodiment of the present invention, wherein an elevator mechanismraises and lowers a dispense tube.

FIGS. 2A-2B illustrate a fluid dispensing apparatus according to asecond embodiment of the present invention, wherein an elevatormechanism raises and lowers a fluid reservoir.

FIG. 3 illustrates a method of operating the fluid dispensing apparatusaccording to one embodiment of the present invention.

FIGS. 4A-4B illustrate a fluid dispensing apparatus configured accordingto an alternate embodiment of the present invention.

FIG. 4C illustrates a method of operating the fluid dispensing apparatusaccording to an alternate embodiment of the present invention.

FIGS. 5A-5C illustrate one embodiment of a weight verification mechanismfor use with the fluid dispensing apparatus according to one embodimentof the present invention.

FIGS. 6-8 illustrate alternate embodiments of a weight verificationmechanism for use with the fluid dispensing apparatus according to oneembodiment of the present invention.

DETAILED DESCRIPTION

Turning now to the drawings, a fluid dispensing apparatus configuredaccording to one embodiment of the present invention is shown thereinand indicated generally by the number 10. As seen in FIGS. 1A-1B, fluiddispensing apparatus 10 comprises a fluid reservoir 12 having an inlet14 and an outlet 16. The inlet 14 is connected to a fluid supply 30 anda supply tube 34. The outlet 16 is connected to a dispense tube 50. Ingeneral, fluid supply 30 supplies the fluid to be dispensed to fluidreservoir 12. Fluid reservoir 12 discharges fluid through dispense tube50 into one or more bottles or containers.

In the embodiment of FIGS. 1A-1B, fluid reservoir 12 comprises aflexible fluid reservoir that holds a supply of fluid to be dispensed.Because fluid reservoir 12 is flexible, it may expand as fluid is addedfrom fluid supply 30, and contract as fluid is discharged. A sensor 18may be disposed proximate fluid reservoir 12 to monitor and control thevolume of fluid contained within fluid reservoir 12 such that itmaintains a generally constant volume. For example, sensor 18 may detectwhen the level of the fluid in fluid reservoir 12 falls below apredetermined level, and generate a signal to processor 40 that causesfluid supply 30 to supply additional fluid. When the fluid level returnsto the predetermined level, sensor 18 generates a signal to processor 40to stop the flow of fluid from fluid supply 30. A support bracket 20supports the weight of fluid reservoir 12, and includes one or moresupports 22 that connect to fluid reservoir 12. As described in moredetail later, support bracket 20 and supports 22 may be part of amechanism that raises and lowers fluid reservoir 12 to dispense fluid todispensing tube 50, and/or receive fluid from fluid supply 30.

Fluid reservoir 12 is connected to fluid supply 30 by supply tube 34,which may be comprised of compressible silicon tubing. A supply valve36, such as a diaphragm valve or pinch-valve, may be controlled bysolenoid 38 and processor 40 to alternately compress and release supplytube 34 to control the flow of fluid from fluid supply 30. The processor40 may generate the control signals to control supply valve 36responsive to signals received from sensor 18, for example.Alternatively, processor 40 may use the signals from sensor 18 tocontrol a pump 42. A filter 44 may be disposed along supply tube 34 toremove any particulate matter or bacteria from the fluid entering fluidreservoir 12.

The dispense tube 50 includes a dispense outlet 52 for dispensing fluidsinto bottles or containers. According to the present invention, fluid isdispensed when the dispense outlet 52 is in a lowered dispensingposition, and not dispensed when dispense outlet 52 is in a raisedfilling position. The dispense tube 50 may be connected to an elevatormechanism 80 that raises and lowers the dispense tube 50. Alternatively,elevator mechanism 80 may raise or lower fluid reservoir 12.

The elevator mechanism 80 comprises a coupler 82 that couples thedispense tube 50 to a vertical shaft 84. Processor 40 controls anactuator 86, such as a motor for example, that raises and lowers thecoupler 82 along the vertical shaft responsive to a signal from a timer88. As the coupler 82 ascends and descends along the shaft 84, thevertical position of dispense outlet 52 changes. Moving dispense outlet52 changes the relative vertical displacement between dispense outlet 52and outlet 16. In FIG. 1A, elevator mechanism 80 has raised dispenseoutlet 52 such that it is in the raised filling position. In thisconfiguration, no fluid is dispensed. In FIG. 1B, however, elevatormechanism 80 has lowered dispense outlet 52 such that it is in thelowered dispensing position. In this configuration, fluid is dispensedfrom the dispense outlet 52 into one or more bottles or containers.

FIGS. 2A and 2B illustrate another embodiment of the present inventionwherein elevator mechanism 80 raises and lowers the fluid reservoir 12instead of the dispense tube 50. This embodiment differs structurallyfrom the previous embodiment in that fluid reservoir 12 comprises anon-flexible tank having a rigid sidewall structure that holds the fluidreceived from fluid supply 30. In addition, a breather bag 24 may beconnected to a vent on fluid reservoir 12 to compensate for the varyingpressure as fluid is added to and removed from fluid reservoir 12. Ifdesired, a filter 26 may be disposed between the breather bag 24 and thevent on fluid reservoir 12 to ensure that the fluid inside of the fluidreservoir 12 remains free of particulates. Optionally, breather bag 24may be removed where filter 26 is a sterilizing grade filter.

In this embodiment, actuator 86 is coupled to support bracket 20.Actuator 86 raises and lowers the support bracket 20 and the fluidreservoir 12 responsive to processor 40 and timer 88. As in the previousembodiment, raising and lowering fluid reservoir 12 changes the relativevertical displacement between dispense outlet 52 and outlet 16 such thatdispense outlet 52 is positioned in the lowered dispensing position todispense the fluid (FIG. 2B), and positioned in the raised fillingposition to stop dispensing the fluid (FIG. 2A). In addition, elevatormechanism 80 may also be responsive to signals generated by sensor 18.Particularly, elevator mechanism 80 may raise fluid reservoir 12whenever sensor 18 detects that the fluid level within fluid reservoir12 has reached a predetermined level. The fluid is dispensed and, whentimer 88 expires, elevator mechanism 80 may lower fluid reservoir 12 tostop dispensing the fluid.

FIG. 3 illustrates a method 100 of operating the fluid dispensingapparatus 10. It should be noted that the method of FIG. 3 is discussedin terms of the embodiment shown in FIGS. 1A-1B. However, this is forillustrative purposes only. The method of FIG. 3 may equally be appliedto the embodiment shown in FIGS. 2A-2B.

The method begins when the dispense outlet 52 is in the raised fillingposition (FIG. 1A). In this configuration, no fluid is dispensed. Whenprocessor 40 receives a signal to begin a dispense cycle (box 102),processor 40 generates a control signal to actuator 86. The actuator 86may then lower coupler 82 along shaft 84 responsive to the controlsignal (box 104). Processor 40 may also generate a control signal tostart a timer (box 106). Dispense outlet 52 descends along shaft 84 and,when it reaches the lowered dispensing position, dispenses the fluid inthe dispense tube into a container (FIG. 1B). When the timer expires(box 108), processor 40 generates a control signal that causes actuator86 to raise the dispense outlet 52 back to its starting position (box110).

FIGS. 4A-4C illustrate another alternate embodiment of the presentinvention that dispenses a predetermined volume of fluid into one ormore bottles or containers. Structurally, the embodiment of FIGS. 4A-4Bdiffers from the previous embodiments in that fluid reservoir 12 isrigid and a breather bag 24 connects to fluid reservoir 12 by areservoir vent tube 28. Where the apparatus 10 does not include breatherbags 64 and/or 24, optional filters 25 and/or 68 may be used to preventparticulate matter from contaminating the fluid. A reservoir vent valve27 is responsive to solenoid 29 and processor 40, and alternately opensand closes to control the flow of fluid into and out of fluid reservoir12. Particularly, when reservoir vent valve 27 is in the open position,fluid may flow freely into and out of reservoir 12. When reservoir ventvalve 27 and supply valve 36 are closed, however, fluid does not flowinto or out of fluid reservoir 12.

Additionally, dispense tube 50 includes a measuring portion 56 thatmeasures and holds a predetermined volume of fluid to be dispensed. Abreather bag 64 compensates for varying pressures in measuring portion56, while solenoid 66 and processor 40 open and close dispense ventvalve 87. When the dispense vent valve 87 is open, fluid may freely flowinto and out of measuring portion 56. In the closed position, fluid isprevented from flowing out of measuring portion 56.

The embodiment of FIGS. 4A-4B also include an upper sensor 58, a lowersensor 60, and a dispense sensor 62, each of which may becommunicatively connected to processor 40. The sensors 58, 60, and 62may cooperate to control the fluid dispensing operations. As seen inFIG. 4A, the dispense sensor 62 is positioned above the upper and lowersensors 58, 60, but below sensor 18. Additionally, dispense sensor 62 isconnected to coupler 82 such that it ascends and descends along shaft 84in conjunction with dispense tube 50. Sensors 58 and 60 are in fixedpositions proximate the measurement portion 56 of dispense tube 50.

FIG. 4C illustrates a method 120 of operating the fluid dispensingapparatus 10 according to the embodiment of FIGS. 4A-4B. Prior todispensing a predetermined volume of fluid, reservoir vent valve 27 andsupply valve 36 are opened to allow fluid to flow from the fluid source30 into the fluid reservoir 12 (box 122) as determined by sensor 18 (box124). Supply valve 36 closes when sensor 18 detects the rising fluidlevel in the fluid reservoir 12, and the dispense tube vent valve 87 isopened allowing fluid to enter the dispense tube 50 (box 126). The fluidin the dispense tube 50 rises until upper sensor 58 detects the fluid(box 128). Sensor 58 then generates one or more signals to processor 40to close dispense tube vent valve 87 and lower the dispense outlet (box130). The fluid rises in the dispense tube 50 to the level of dispensesensor 62. Upon detecting the fluid, (box 132), dispense sensor 62generates a signal to close reservoir vent valve 27 to stop the flow offluid into the dispense tube 50 (box 134). The dispense tube 50 nowholds a predetermined volume of fluid to be dispensed.

Processor 40 controls actuator 86 to lower dispense tube 50 alongvertical shaft 84 responsive to the signal generated by the upper sensor58. This lowers dispense outlet 52 to the lowered dispensing position.Once dispense outlet 52 is lowered into position (box 136), dispensetube vent valve 87 is opened to allow the fluid to drain into thecontainer or bottle (box 138). Lower sensor 60 detects the falling fluidlevel in dispense tube 50 as the fluid drains into the container orbottle (box 140), and generates a signal to close dispense tube ventvalve 87 (box 142). This stops the fluid from draining from dispensetube 50. Lower sensor 60 also generates a signal to processor 40 toraise dispense tube 50 along vertical shaft 84 to return it to itsoriginal raised filling position (box 144).

Therefore, elevator mechanism 80 may be responsive to one or moresensors or timers to dispense or not dispense a fluid by changing therelative vertical displacement between the dispense outlet 52 and theoutlet 16 on fluid reservoir 12. Particularly, elevator mechanism 80 mayraise and lower the dispense tube 50 and/or reservoir 12, as shown inthe previous embodiments, to change the relative vertical displacementbetween the dispense outlet 52 and the outlet 16. The elevator mechanism80 may also be used to adjust the relative vertical positions of one ormore of the measuring portion 56, the dispense portion, and the fluidreservoir 12. Particularly, the measuring portion 56, the dispenseportion, and the fluid reservoir 12 may be raised and loweredindependently of each other to effect their proper relative verticalpositions any time during the filling-dispensing operations.Additionally, elevator mechanism 80 could also be responsive to othersensors such as a sensor associated with the weight verificationmechanism 150 shown in FIGS. 5A-5C.

Weight verification mechanism 150 comprises a chamber 152 that containsa liquid medium 154. The liquid medium 154 may be, for example, asilicone liquid that does not readily evaporate at operatingtemperature. A displacement float 156 is disposed at least partiallyinside of chamber 152, and floats on liquid medium 154. Weighverification mechanism 150 further includes a platform 158 that connectsto displacement float 156 by a platform support 160. A bushing 162 maybe disposed on platform support 160 to prevent the sides of displacementfloat 156 from contacting the interior walls of chamber 152. A sensor164 is movably attached to a sensor mount 166, and generates signals forprocessor 40 based on the detected level of liquid medium 154.

As seen in FIG. 5B, placing an empty container 170 on platform 158causes displacement float 156 to sink slightly in liquid medium 154. Thedisplaced volume of liquid medium 154 rises between the outer wall ofdisplacement float 156 and interior wall of chamber 152. Processor 40generates a control signal to move sensor 164, which was previously setto monitor the level of the liquid medium 156 associated with nocontainer 170 (FIG. 5A), to the new level of liquid medium 154associated with the empty container 170 (FIG. 5B). Sensor 164 detectsthe new level of liquid medium 154 and generates a signal to processor40. Processor 40 may then control elevator mechanism 80 to lowerdispense tube 50 to the lowered dispensing position.

Processor 40 calculates what the level of liquid medium 154 should bewhen container 170 is full of fluid, and moves sensor 164 to thatposition (FIG. 5C) while fluid is being dispensed. This positionrepresents a level at which the displaced liquid medium 154 isproportional to the predetermined volume of fluid to be dispensed. Whensensor 164 detects the rising level of the liquid medium 154, itgenerates a signal that causes processor 40 to control elevatormechanism 80 to stop dispensing the fluid into container 170.Particularly, elevator mechanism 80 may raise dispense tube 50 such thatdispense outlet 52 returns to the raised filling position above outlet16. If the level of the liquid medium 154 is lower than the expectedlevel, processor 40 may calculate the volume of additional fluid needed,and move sensor 164 to a new position. Additional fluid equal to thesubsequently calculated volume may then be dispensed into container 170by controlling elevator mechanism 80 to lower dispense tube 50.Conversely, if the level of the liquid medium 154 is higher than theexpected level calculated by processor 40, the container may be removedmanually or mechanically.

FIGS. 6 and 7 illustrate alternate embodiments of the weightverification mechanism 150. The embodiments of FIGS. 6 and 7 include apivot 168. Further, the weight verification mechanism 150 of FIG. 7includes an arcuate chamber 152, displacement float 154, and sensormount 166. In these embodiments, sensor 164 detects a falling level ofthe liquid medium 154 as container 170 fills with fluid dispense outlet52.

FIG. 8 illustrates another embodiment of the weight verificationmechanism 150 wherein the chamber 152 comprises a flexible bag filledwith the liquid medium 154. When container 170 is placed on platform158, sensor 164 moves along sensor mount 166, and detects thedisplacement of the liquid medium 154 as previously described.

It should be noted that the drawings illustrate the elevator mechanism80 as raising the dispense tube 50 to a level where the dispense outlet52 remains below the level of the fluid in the fluid reservoir 12. Thismight prevent the need to have to fully recharge the dispense tube 50with fluid after each dispensing cycle. Particularly, after the elevatormechanism 80 raises the dispense tube 50, some amount of fluid mayremain inside the dispense tube. Raising the dispense tube 50 such thatthe dispense outlet 52 remains below the fluid level in the fluidreservoir 12 could prevent or inhibit this remaining fluid from drainingback into the fluid reservoir 12. Thus, the dispense tube 50 may remain“primed” with some amount of fluid. This might negate the need to fullycharge the dispense tube 50 with fluid prior to each dispensing cycle.However, those skilled in the art will readily appreciate that raisingthe dispense tube 50 such that the dispense outlet 52 remains below thelevel of fluid in the fluid reservoir is not required by the presentinvention. The elevator mechanism 80 may raise the dispense tube 50and/or reservoir 12 to any level desired.

The present invention may, of course, be carried out in other ways thanthose specifically set forth herein without departing from essentialcharacteristics of the invention. The present embodiments are to beconsidered in all respects as illustrative and not restrictive, and allchanges coming within the meaning and equivalency range of the appendedclaims are intended to be embraced therein.

1. A fluid dispensing apparatus to dispense a predetermined volume offluid comprising: a fluid reservoir connected to a fluid supply; adispense tube connected to an outlet port on the fluid reservoir, thedispense tube comprising a measurement portion to measure apredetermined volume of fluid to be dispensed, and a dispense portionincluding a dispense outlet to dispense the predetermined volume offluid; an elevator mechanism to change a relative vertical displacementbetween the dispense outlet and the outlet port on the fluid reservoir;and a processor programmed to: control the elevator mechanism to raisethe dispense tube to a raised filling position to prevent fluid flowfrom the dispense outlet; fill the dispense tube with the predeterminedvolume of fluid from the fluid reservoir; and control the elevatormechanism to lower the dispense tube to a lowered dispensing position todispense the predetermined volume of fluid.
 2. The dispensing apparatusof claim 1 further comprising a dispense vent valve communicativelyconnected to the dispense tube, and configured to move between an openposition and a closed position to control the flow of the fluid into andout of the dispense tube.
 3. The dispensing apparatus of claim 2 whereinthe processor is further programmed to: open the dispense vent valvewhen the dispense tube is in the raised filling position to allow fluidto flow into the measurement portion of the dispense tube; close thedispense tube vent valve to prevent the fluid from flowing out of themeasurement portion; and open the dispense vent valve when the dispensetube is in the lowered filling position to allow the fluid to flow outof the measurement portion of the dispense tube.
 4. The dispensingapparatus of claim 1 wherein the elevator mechanism comprises a verticalshaft operatively connected to the dispense tube, and wherein theprocessor is programmed to control the elevator mechanism to selectivelyraise or lower the dispense tube along the vertical shaft to change avertical position of the dispense outlet relative to the position of anoutlet port on the fluid reservoir.
 5. The dispensing apparatus of claim4 further comprising a dispensing sensor that is raised or lowered alongthe vertical shaft with the dispense tube, and wherein an upper sensorgenerates one or more signals to selectively lower the dispense tube,and a lower sensor generates one or more signals to selectively raisethe dispense tube.
 6. The dispensing apparatus of claim 1 wherein theprocessor is programmed to control the elevator mechanism to selectivelychange the relative vertical displacement between the dispense outletand an outlet port on the fluid reservoir responsive to a detectedvolume of fluid that has been dispensed, the expiration of a timer, or adetected volume of fluid in the measurement portion of the dispensetube.
 7. The dispensing apparatus of claim 1 further comprising: adispensing sensor disposed on the dispense portion to detect when thepredetermined volume of fluid is in the dispense tube; an upper sensordisposed proximate the measurement portion and below the dispensingsensor to detect a rising volume of fluid in the measurement portion ofthe dispense tube; a lower sensor disposed proximate the measurementportion and below the upper sensor to detect a falling volume of fluidin the measurement portion of the dispensing tube; and a reservoirsensor disposed proximate the fluid reservoir and above the upper sensoron the measurement portion of the dispense tube to detect a volume ofthe fluid in the fluid reservoir.
 8. The dispensing apparatus of claim 7wherein the upper sensor generates a signal to effect the flow of fluidfrom the fluid reservoir responsive to detecting the rising volume offluid in the measurement portion.
 9. The dispensing apparatus of claim 7wherein the elevator mechanism lowers the dispense tube and thedispensing sensor responsive to a signal generated by the upper sensor,and raises the dispense tube and the dispensing sensor responsive to asignal generated by the lower sensor.
 10. The dispensing apparatus ofclaim 1 wherein the elevator mechanism is further configured to raise orlower one or more of the measurement portion, the dispense portion, andthe fluid reservoir independently,
 11. A method of dispensing apredetermined volume of fluid comprising: providing a fluid reservoirhaving an outlet port with fluid from a fluid supply; connecting adispense tube to the fluid reservoir, the dispense tube comprising ameasurement portion to measure a predetermined volume of fluid to bedispensed, and a dispense portion including a dispense outlet todispense the predetermined volume of fluid; controlling an elevatormechanism to raise the dispense tube to a raised filling position toprevent fluid flow from the dispense outlet; filling the dispense tubewith the predetermined volume of fluid from the fluid reservoir; andcontrolling the elevator mechanism to lower the dispense tube to alowered dispensing position to dispense the predetermined amount offluid from the dispense outlet.
 12. The method of claim 11 furthercomprising: connecting a dispense vent valve to the dispense tube; andopening and closing the dispense vent valve to control the flow of thefluid into and out of the dispense tube.
 13. The method of claim 12further comprising: generating a first signal to open the dispense ventvalve when the dispense tube is in the raised filling position to allowfluid to flow into the measurement portion of the dispense tube;generating a first signal to close the dispense tube vent valve toprevent the fluid from flowing out of the measurement portion; andgenerating a first signal to open the dispense vent valve when thedispense tube is in the lowered filling position to allow the fluid toflow out of the measurement portion of the dispense tube.
 14. The methodof claim 11 wherein raising or lowering the dispense tube is doneresponsive to a detected volume of fluid that has been dispensed, theexpiration of a timer, or a detected volume of fluid in the measurementportion of the dispense tube.
 15. The method of claim 11 furthercomprising raising or lowering a sensor with the dispense tuberesponsive to the sensor detecting a specified volume of fluid in themeasurement portion of the dispense tube.
 16. The method of claim 11further comprising raising or lowering the fluid reservoir to maintainthe fluid in the fluid reservoir at a predetermined volume.
 17. Themethod of claim 11 further comprising: generating a signal to effect theflow of fluid from the fluid reservoir into the dispense tube responsiveto detecting when a rising volume of fluid reaches a specified level inthe measurement portion of the dispense tube; generating a signal tolower the dispense tube to dispense the predetermined volume of fluidresponsive to detecting when the dispense tube contains thepredetermined volume of fluid; and generating a signal to raise thedispense tube responsive to detecting a falling level of fluid in thedispense tube.
 18. The method of claim 11 further comprisingindependently raising or lowering one or more of the measurementportion, the dispense portion, and the fluid reservoir.